Telephone-exchange system.



L. HJOHNSON.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED DEC. l. 1915.

1,203,742. PatentedN0v.7,1916.-

//1 [Zen/or.- L e W/ls H Johnson.

LEWIS H. JOHNSON, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Application filed December 1, 1915.

To all whom it may concern Be it known that I, Lnwls Howns JOHN- son, a citizen of the United States, residing at Bloomfield, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description. V

This invention relates to telephone exchange systems and more particularly to such systems of the central energy type, the object of this invention being to provide inn-- proved and simplified signaling means for such systems by which service is greatly improved.

In telephone systems heretofore devel oped, means have been provided whereby,

when the receiver has been restored to and subsequently removed from the switchhook at a substation, a circuit interrupting device is brought into operative relation to a signaling device, causing the signaling device to furnish a characteristic signalcommonly known as a recall signal-to the operator.

The present invention is an improvement Figure 1 shows ordinary subscribers sub- 4 station apparatus and line circuits A. and B,

and a cord circuit C, embodying the present invention, used to interconnect the subscribers lines for conversation; and Fig. 2 shows a cord circuit embodying the present invention in which there are two relays for automatically controlling the flashing of the supervisory signals.

Assuming that subscriber A wishes to con verse with subscriber B, A will signal the central oflice in the usual manner, whereupon the operator will iiisert the answering plug of the cord circuit G into the jack associated with As line, completing a circuit for supervisory lamp 7 and causing the op eration of supervisory relay 5. The operation of supervisory relay 5 completes a cir:

Specification of Letters Yatent.

Patented Nov. 7, 1916.

Serial No. 64,430.

cuit from battery through interrupter 6, normal right-handcontact of relay 9, contact of supervisory relay 5, normal left-hand contact of relay 9, resistances at and 12, sleeve contacts of the answering plug and jack, and the winding of cut-off relay 13 to ground. The interrupter 6 and resistance 4 are-now connected in multiple with the lamp 7 which will flash intermittently until the actuation of listening key 8. The operator then operates listening key 8 to connect the operators telephone set to the talking strands of the cord circuit C. Actuation of listening key 8 causes the operation of relay 9 over circuit from battery through the right-hand winding of relay 9 and the middle contact of listening key 8 to ground. Relay 9 in operating removes interrupter 6 and resistance 4: from multiple relation with the lamp 7, and completes a locking circuit for itself, which may be traced from battery through the right-hand alternate contact of relay 9, contact of relay 5, contact 11 of relay 9, left-hand winding thereof, resistance 12, sleeve contacts of the answering plug and jack and the winding of cut-off relay 13 to ground. When supervisory lamp 7 is included in circuit with resistance 12 only, the lamp will receive suflicient current to light it, but when the lamp is shunted by resistance 4 or the left-hand winding of relay 9, it will not receive suiticient current. Finding the desired numberto be that of subscriber B, the operatorinserts the calling plug of the cord circuit (7 into the jack associated with Bs line, restores listening key 8 to normal position and actuates ringing key 14 to send ringing current out over Bs lineto operate the call bell thereat. When the calling plug is inserted into the jack of BS line, the supervisory signal 16 is lighted due to a circuit from battery through supervisory lamp 16, resistance 17, sleeve contacts of the calling plug and jack, and the winding of cut-off relay 18 to ground. Upon the response of subscriber B to the sounding of the call bell, supervisory relay 19 is operated, whereupon supervisory lamp 16 is extinguished.

After the operator has inserted the calling plug of cord circuit G into the jack of Bs line, and has restored the listening key 8 to normal position, should subscriber A, for

any reason, deslre to attract the attention of the operator, he will merely depress the switchhook, and then permit it to rise again, thereby causing Supervisory lamp 7 to flash. When the switchhook is depressed, supervisory relay 5 releases, thereby opening the locking circuit of relay 9, which in turn rcleases. When the switchhook is subsequently raised, supervisory relay 5 is again energized, whereupon the interrupter 6 and resistance 4 are again brought into multiple relation with supervisory lamp 7 to cause the intermittent flashing thereof. The operator observing the flashing of lamp 7 may now actuate the listening key 8 to connect the operators telephone set to the talking strands of the cord circuit, and in so doing causes relay 9 to operate and lock up, there- 'by retiring the signal, as before explained.

Assuming that the cord circuit shown in Fig. 2 had been used in establishing telephonic connections from subscriber A to subscriber B, the insertion of the answering plug of this cord circuit into the jack of As line in response to the operation of the line signal thereof, supervisory relay 30 opcrates, whereupon interrupter 31 and resistance 44 are brought into multiple relation with supervisory lamp 32 to cause the lamp to flashintermittently. The operator then actuates listening key 33 to connect the operators telephone set to the talking strands of this cord circuit. The actuation of listening key 33 causes the operation of relays 34 and 35 over a circuit from battery throughthe winding of relay 34, right-hand winding of relay and middle contact of listening key 33 to ground. The operation of relay 35 interrupts the multiple relation of interrupter 31 and supervisory lamp 32, whereupon supervisory lamp 32 ceases to flash. Relays and 35 in operating also complete a locking circuit therefor from battery through the. winding of relay 34, alternate right-hand contact of relay 35, contact of relay 30, contact 36 of relay 35, lefthand winding of relay 35, resistance 37, sleeve contacts of the answering plug and jack and the winding of cut-off relay 13 to 'ground. The operator, after learning that subscriber A desires to be connected to subscriber Bs line, inserts thecalling plug into the jack associated with Bs line, restores listening key'33 to its normal position and actuates ringing key 38 to send ringing current over the line to operate the call bell at the substation. The insertion of the calling plug into the jack causes the lighting of su PQI'VlSOlY'lLHIP 39 over a circuit from battery through lamp 39, resistance 40, sleeve contacts of the calling plug and jack and the winding of cut-off relay 18 to ground. Subscriber B, in removing the receiver from the switchhook in response'to the operation of the call bell, causes the operation of supervisory relay 41, which in operating eX- tmguishes superv sory lamp 39 and completes a second locking circuit for relay 34 from battery through the winding of relay 34, contact 42 thereof, contact of supervisory relay 41, resistances 43 and 40, sleeve contacts of the calling plug and jack, and the would restore the receiver to the switchhool:

and then remove the receiver therefrom, thereby causing supervisory signal 32 to flash intermittently to furnish a recall signal to the operator. When the receiver was restored to the switchhook, supervisory relay 30 released, thereby opening the locking circuit of relay 35, which released. Relay 34, however, did not release for the second locking circuit therefor was closed. The subsequent removal of the receiver from the switchhook by subscriber A causes the 01 eration of supervisory relay 30, thereby completing a circuit from battery through interrupter 31, normal. right-hand contact of relay 35, contact of relay 30, normal left hand contact of relay 35, resistances 44 and 37, sleeve contacts of the answering plug and jack, and the winding of cut-elf relav to ground. The portion of this circuit up to and including resistance 44 is in multiple relation with battery and supervisory signal 32, so that supervisory lamp 32 is caused to flash;

Suppose that after conversation is completed subscriber B should desire to make a call before the calling plug of the cord circuit is removed from the jack of Bs line. The restoration of the receivers to the switchhooks at the completion of the conversation causes the release of supervisory relays 30 and 41, whereupon relays 34 and. 35 released. Subscriber B then removing his receiver from the switchhook to make a call, before the calling plug is removed from the ack, causes the operation of supervisory relay 41, Which connects interrupter 31 and resistance 43 in multiple relation with supervisory lamp 39, which is thereupon caused to flash intermittently. In response to the flashing of'supervisory signal 39, the operator actuates listening key 33 to connect tele phone set to the talking strands of the cord to find out what subscriber B desires. The actuation of listening key 33 causes the open ation of relay 34, which in operating removes the interrupter from multiple rela tion with the supervisory signal 39 and completes a locking circuit for itself from battery through the Winding of relay 34, contact 42 thereof, contact of relay 41, resistances 43 and 40, sleeve contacts of the calling plug and jack, andthe winding of cutoff relay 18 to ground. It is to be noted that the calling supervisory lamp 39 cannot be caused to automatically flash intermittently unless the calling subscriber has restored the receiver to the switchhook.

It is to be observed that when the receiver is restored to the switchhook by subscriber A, in case the cord circuit C has been used in connecting lines A and B, the supervisory lamp 7 will be lighted to furnish a disconnect signal. In case the cord circuit shown in Fig. 2 has been used to connect lines A and B, the restoration of the receivers to the switchhooks will cause supervisory lamps 32 and 39 to be lighted to furnish disconnect signals. In each case the disconnect signal is distinguished from a recall signal in that the disconnect signal is a continuous lighting of the lamps while a recall signal is the intermittent lighting of the lamps.

Causing the supervisory lamp on the answering end of the cord circuit to be lighted intermittently whenever the answering plug is connected to the calling line, serves a very important function. In telephone systems heretofore used, an operator, while busy completing connection, may observe a lighted condition of another line lamp and may insert the answering plug of another cord circuit in the jack associated with the second calling line. After having completed the connection between the first calling line and the line called thereby, the

operator may and frequently does forget that the answering plug of a second cord circuit has been inserted in the jack of the second calling line. The only means for attracting the operators attention is for the subscriber to repeatedly lower and raise the switchhook to produce intermittent lighting of the answering supervisory signal. This is rather annoying to the subscriber, and also time-consuming. This present invention overcomes the objectionof the systems heretofore used by causing the answering supervisory lamp to be lighted intermittently whenever an answering plug is inserted into the jack of a calling line, pro- I vided the listening key associated with that cord circuit is not actuated.

lVhat is claimed is:

1. A. telephone exchange system comprising a plurality of telephone lines extending from substations to the central ofiice, a link circuit thereat for interconnecting said lines, a supervisory relay associated with the link circuit and adapted to be controlled from.a connected substation, a supervisory signaling device. a listening key associated with the link circuit, a second relay energized by the actuation of the listening key, locking circuit therefor closed by its energiiation, the de'e'nergization of the supervisory relay causing the deenergization of the second relay, and an interrupter brought into operative relation with the supervisory signaling device by the subsequent energization of the supervisory relay to cause the signaling device to furnish an intermittent signal.

A telephone exchange system comprising a plurality of telephone lines extending from substations to the central. office, a link circuit thereat for interconnecting said lines, a supervisory signaling device, a

supervisory relay associated with the link circuit and controlled from a connected substation, a listening key associated with the link circuit, a second relay energized by the actuation of the listening key, a locking circuit therefor closed by its energization and including a contact of the operated supervisory relay, the deenergization of the supervisory relay causing the deenergization of the second relay, and an interrupter brought into multiple relation with the supervisory signaling device by the subsequent energization of the supervisory relay when the second relay is deenergized to cause the signaling device to furnish an intern'iittent'signal.

3. A telephone exchange system compris ing a plurality of telephone lines extending from. substations to the central oiiice, a link circuit thereat for interconnecting said lines, a supervisory relay associated with the link circuit and adapted to be controlled from a connected substation, a second relay, an interrupter, a supervisory signaling device, said supervisory relay operating upon connection of the link circuit with a calling telephone line to operatively associate the interrupterwith the signaling device thereby causing said signaling device to furnish an intermittent signal, a listening key, actuation thereof causing the energization of the second relay to interrupt the operative association of the signaling device and the interrupter, and a locking circuit for the second relay closed by the energization thereof, the deenergization of the supervisory relay causing the deenergization of the second relay and a subsequent energization of the supervisory relay operatively associating the interrupter and naling device to cause the signaling device to furnish an intermittent signal.

at. A telephone exchange system comprising a plurality of telephone lines extending from substations to a central oilice, a link circuit thereat for interconnecting said lines, a. supervisory relay associated with the link circuit and adapted to be controlled from a connected substation, a second relay, an interrupter, a supervisory signaling device, said supervisory relay operating upon connection of the link circuit with a calling telephone line to operatively associate the interrupter with the signaling device thereby causing said signaling device to furnish an intermittent signal, and a listening key,

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actuation thereof causing the energization of the second relay to interrupt the operative association of the signaling device and the interrupter.

5. A telephone exchange system comprising a calling and called. telephone line extending from substations to a central oflice, a link circuit thereat interconnecting said lines, a supervisory relay associated with each end of the link circuit and adapted to be controlled from the respective connected substations, a supervisory signaling device, a listening key associated with the link circuit, a second and a third relay energized by the actuation of the listening key, a locking circuit for the second and third relays closed by the energization of the second relay when the supervisory relay associated with the answering end of the link circuit is energized, a second locking circuit for the third relay closed by the energization of the supervisory relay associated with calling end of therlink circuit, and an interrupter brought into operative relation to the signaling device by the deenergization of the supervisory relays and the subsequent energization of the supervisory relay associated with the calling end of the link circuit.

6. A telephone exchange system comprisin a calling and :1 called telephone line extending from the substations to a central office, a link circuit thereat interconnecting said lines, a supervisory relay associated with each end of the link circuit and adapted to be controlled from the respective connected substations, a supervisory signaling device for each end of the link circuit,

a listening key, a second and a third relay energized by the actuation of the listening key, a locking circuit for the second and third relays closed by the energization of the second relay when the supervisory relay associated with the answering end of the link circuit is energized, a second locking circuit for the third relay closed by the energization ofthe other supervisory relay,

and an interrupter brought into operative relation to the answering supervisory signal by the deenergization and subsequent energization of the answering supervisory relay and to the calling supervisory signal by the deenergization and subsequent energization of the calling supervisory relay.

7. A telephone exchange system comprising a plurality of telephone lines extending from substations to a central office, a link circuit thereat for interconnecting saidlines, a supervisory relay associated with the link circuit and adapted to be controlled from a connected substation, a supervisory signaling device, an operator controlled key associated with the link circuit, a second relay energized by the actuation of the key, a locking circuit therefor closed by its energization, the deenergization of the supervisory relay causing the deenergization of the second relay, and an interrupter brought into operative relation with the supervisory signaling device by thesubsequent energization of the supervisory relay to cause the signaling device to furnish an intermittent signal.

8. A telephone exchange system comprising a calling and a called telephone line extending from substations to a central oflice, a link circuit thereat interconnecting said lines, a supervisory relay associated with each end of the link circuit and adapted to be controlled from the respective connected substations, a supervisory signaling de vice, an operator-controlled key associated with the link circuit, a second and a third relay energized by the actuation of the key, a locking circuit for the second re lay closed by the energization thereof when the answering supervisory relay is energized, a locking circuit for the third relay closed by the energization thereof when the calling supervisory relay is energized, and an interrupter brought into operative relation to the signaling device by the deenergization of the supervisory relays and the subsequent energization of the calling supervisory relay.

9. A telephone exchange system comprising a calling and a called telephone line extending from substations to a central office, a link circuit thereat interconnecting said lines, a supervisory relay associated with each end of the link circuit and adapted to be controlled from the respective connected substations, a supervisory signaling device for each end of the link circuit, an operatorcontrolled key associated with the link circuit, a second and a third relay energized by the actuation of the key, a locking circuit for the second relay closed by the energization thereof when the answering LEWIS I-I. JOHNSON.

Qopies of this patent may be obtained for five cents each, by addressing the Commissioner of ;Patents, Wa i on 9- 

